Container base



FIG. 1 is a bottom perspective view of a container base showing our new design;

FIG. 2 is a bottom plan view thereof;

FIG. 3 is a top plan view thereof; and,

FIG. 4 is a side elevation view.

Any broken lines in the drawings depict probable environment only and form no part of the claimed design. 

The ornamental design for a “container base,” as shown and described. 